1. Technical Field
The present invention relates to an electrostatic discharge protection device and a composite electronic component including the same, and more particularly, to an electrostatic discharge protection device useful for a high speed transmission system or complexation with a common mode filter, and a composite electronic component including the same.
2. Description of the Related Art
Recently, miniaturization and high performance of electronic apparatuses have rapidly progressed. In addition, as generally represented by a high speed transmission system such as USB 2.0, S-ATA2, HDMI, or the like, the progress toward a high speed of a transmission rate (a high frequency exceeding 1 GHz) and a low driving voltage has been remarkably conducted.
On the other hand, in accordance with the miniaturization or the low driving voltage of the electronic apparatuses, withstand voltage of electronic components used in the electronic apparatuses is lowered. Therefore, a protection of the electronic components from overvoltage generally represented by an electrostatic pulse generated when a person's body contacts a terminal of the electronic apparatus is an important technical problem.
As the related art regarding an electrostatic discharge protection device, there is Japanese Patent Laid-Open Publication No. 2012-18902, which discloses an electrostatic discharge protection device 100 including an insulating substrate 11, a pair of electrodes 21 and 22 disposed on the insulating substrate 11 so as to be spaced apart from each other and face each other, a functional layer 31 disposed between the electrodes 21 and 22, and a plurality of intermediate electrodes 41 using the functional layer 31 and disposed so as to be spaced apart from the pair of electrodes 21 and 22, as shown in FIG. 1.
According to the above-mentioned patent, the functional layer 31 having a desired thickness is formed by using insulating inorganic materials 32 and conductive inorganic materials 33 and applying a publicly known method of forming a thin film, such as a vacuum deposition method, a reactive deposition method, a sputtering method, an ion plating method, a vapor method such as a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or the like, on an insulating surface 11a and/or the electrodes 21 and 22 of the insulating substrate 11. For the functional layer 31, a composite in which the conductive inorganic materials are irregularly dispersed in a matrix of the insulating inorganic materials is used.
Therefore, in the case of including the functional layer 31 as in the above-mentioned patent, processes such as a thin film deposition, a filler dispersion, and the like, are added in order to add the insulating inorganic materials 32 and the conductive inorganic materials 33, such that the processes are complicated, and the productivity is deteriorated.
In addition, it can be appreciated from FIG. 2 that the conductive inorganic materials 33 are dispersed over the pair of electrodes 21 and 22, and an interval G therebetween. In the above-mentioned structure, there is the possibility that the conductive inorganic materials 33 will be irregularly dispersed in the insulating layer, such that a problem may occur in accurately designing withstand voltage, which is not preferable.
In addition, in the patent, an intermediate electrode (not shown) of the interval G between the electrodes, in addition to the pair of electrodes 21 and 22, is additionally included. As shown in FIG. 1, the pair of electrodes 21 and 22 are formed to be spaced apart from each other by a predetermined interval G, and the interval G has a range of 0.1˜50 μm. That is, in the patent, the intermediate electrode, the conductive inorganic materials 33, or the like, in addition to the pair of electrodes 21 and 22, are used to secure withstand voltage characteristics.